As far back as the 1500s, one meaning of the word �bucket' was a beam or yoke on which things could be hung or carried, based on the Old French word �buque' or �buquet' meaning a balance. Shakespeare himself uses the word in this sense when Falstaff says: "...he that gibbets on the brewer's bucket" in �Henry IV Part 2' Act 3 Scene 2. (Since �gibbet' meant to hang/dangle, this is clearly not a reference to a pail-type bucket!)
One use for such a bucket was to hang animals by their heels for slaughter. Of course, in their death-struggle, they would �kick the bucket' and that is where we get the phrase which means �to die'. It has nothing to do with spilling water just drawn up in a bucket from a well or with convicted criminals in the Navy - or suicides - standing on a pail which could then be kicked away, allowing them to be hanged. These are just such fanciful ideas, I'm afraid.